Department of Environmental and Occupational Health, University for Development Studies, Tamale, Ghana.
Research Laboratory in Aquaculture and Aquatic Ecotoxicology, University of Parakou, Parakou, Benin.
PLoS One. 2024 Oct 21;19(10):e0312273. doi: 10.1371/journal.pone.0312273. eCollection 2024.
Pesticides are chemicals used to enhance crop production. However, their residues can persist and accumulate in various environmental settings. This study assessed the occurrence of pesticide residues and ecological risks in surface water and sediment from the Libga and Builpela dams in northern Ghana. A total of 42 pesticides were analysed. Toxic units were used to assess the acute risk to sediment-dwelling organisms and aquatic biota. Risk quotients were employed to assess the chronic risk to aquatic organisms. Chlorpyrifos, atrazine, profenofos, and chlorfenvinphos were the main chemicals found in surface water. The concentrations were highest near the Builpela dam (0.413μg/L, 2.927μg/L, 0.304μg/L, 0.692μg/L, 0.073μg/L, 0.290μg/L, 0.06μg/L, and absent in the Libga dam). In the sediment, the organophosphates pyrimiphos-methyl and chlorpyrifos were found at high concentrations. They were found in higher quantities in the Libga dam (0.554mg/kg and 0.052mg/kg, respectively) and Builpela dam (0.051mg/kg and 0.043mg/kg, respectively). For organochlorines, p,p'-DDE and p,p'-DDD were the main residues detected at high concentrations. However, concentrations were higher for p,p'-DDD at Builpela than for p,p'-DDE. Additionally, high concentrations of atrazine were detected in this study. The toxic units showed a high acute risk for organisms that live in sediment as a result of chlorpyrifosfos and chlorfenvinphos residues. Similarly, pirimiphos-methyl and chlorfenvinphos, followed by chlorpyrifos, contributed to high acute risk in aquatic invertebrates. Risk quotients showed that both dams had a high long-term risk for aquatic life; however, the risk was higher at the Builpela dam due to Pirimiphos-methyl and Chlorfenvinphos. Ghana's pesticide regulations are less comprehensive and enforcement is often weaker in protecting aquatic organisms. It is recommended to enforce strict limits on pesticide residues. Additionally, there is a need to regularly review and update these regulations based on new scientific data to protect aquatic ecosystems.
农药是用于提高作物产量的化学物质。然而，它们的残留会在各种环境中持续存在和积累。本研究评估了加纳北部利卜加和布利佩拉大坝的地表水和沉积物中农药残留和生态风险。共分析了 42 种农药。采用毒性单位评估底栖生物和水生生物的急性风险。风险商数用于评估水生生物的慢性风险。氯吡硫磷、莠去津、丙溴磷和氯酚磷是地表水中发现的主要化学物质。浓度在布利佩拉大坝附近最高（利卜加大坝：0.413μg/L、2.927μg/L、0.304μg/L、0.692μg/L、0.073μg/L、0.290μg/L、0.06μg/L，布利佩拉大坝：0.073μg/L、0.290μg/L、0.06μg/L，利卜加大坝：0.052mg/kg、0.051mg/kg，布利佩拉大坝：0.043mg/kg、0.051mg/kg）。在沉积物中，发现有机磷杀虫剂嘧啶磷和氯吡硫磷含量较高。利卜加大坝（0.554mg/kg 和 0.052mg/kg）和布利佩拉大坝（0.051mg/kg 和 0.043mg/kg）的含量更高。对于有机氯农药，p,p'-DDE 和 p,p'-DDD 是检测到的主要残留，浓度较高。然而，布利佩拉大坝中 p,p'-DDD 的浓度高于 p,p'-DDE。此外，本研究还检测到高浓度的莠去津。由于氯吡硫磷和氯酚磷的残留，有毒单位显示出对生活在沉积物中的生物的高急性风险。同样，嘧啶磷和氯酚磷，其次是氯吡硫磷，对水生无脊椎动物的高急性风险也有贡献。风险商数表明，两座大坝对水生生物都有很高的长期风险；然而，由于嘧啶磷和氯酚磷，布利佩拉大坝的风险更高。加纳的农药法规不够全面，执法力度往往较弱，无法有效保护水生生物。建议对农药残留实施严格限制。此外，需要根据新的科学数据定期审查和更新这些法规，以保护水生生态系统。
